The invention relates to particles comprising organopolysiloxane gel microparticles and organoaluminum compounds immobilized thereon, to their preparation, and to their use as cocatalysts together with metal compounds from sub-groups 4, 5, 6 and 8-10 of the Periodic Table, for the oligomerization, cyclization or polymerization of olefins.
Aluminoxanes are obtained by controlled hydrolysis of organoaluminum compounds. For example, oligomeric methylaluminoxane is prepared by controlled hydrolysis of trimethylaluminum using water.
Organoaluminoxanes have a broad range of application as cocatalysts in metalcatalyzed olefin oligomerization, cyclization or polymerization using metal compounds from sub-groups 4, 5, 6 and 8-10 of the Periodic Table, where the added organoaluminoxane serves as activator for the catalytically active metal compound. In U.S. Pat. No. 5,206,401, for example, methylaluminoxanes are added to catalytically active metallocene compounds of metals from sub-group 4 of the Periodic Table as activators for olefin polymerization.
When carrying out metal-catalyzed olefin polymerization activated by organoaluminoxane, for example using metallocene or semisandwich catalysts, a recurring problem is that of reactor fouling, i.e. during the reaction, the reactor walls become coated with the polyolefin formed. Temperature control during the reaction is no longer possible. The deposits ultimately result in the reactor blocking up completely. In large-scale industrial production, this results in plant shutdowns and thus high costs. Another problem in the preparation of polyolefins is the morphology of the product obtained. Without further additives, a finely pulverulent product is obtained. For further industrial processing, however, the polymer should be produced in larger particle sizes, preferably having a spherical shape with a mean sphere diameter of 0.1 to 3 mm.
Reactor fouling can be suppressed by carrying out the immobilization of the active catalyst center by applying the cocatalyst, such as methylaluminoxane (MAO) or ethylaluminoxane, to silica gel. This is described, for example, in U.S. Pat. No. 4,925,821. The heterogenization of the cocatalyst means that the actual polymerization-active cationic reaction center is quasi-heterogenized via an ionic interaction with the anionic organoaluminoxane.
The heterogenization is carried out in a multiphase reaction; wetting problems, long reaction times, incomplete reaction and difficult reaction control and end-point determination of the reaction must be accepted. Furthermore, the heterogenization of the cocatalyst causes a significant reduction in the catalytic activity. Likewise, the cocatalyst in metalcatalyzed reactions of olefins must be added in a large excess, namely in a molar ratio of from 1:1000 to 1:20,000. The ratio between catalytically active metal and cocatalyst is rather random and cannot be set precisely.
The object was to provide organoaluminum compound-carrying particles which, when used as cocatalysts together with metal compounds, have high catalytic activity in the polymerization, oligomerization or cyclization of olefins, where it should be possible to control precisely the amount of organoaluminum compound-carrying particles employed, i.e. the ratio between the active metal center and aluminum.
The invention relates to p articles comprising organopolysiloxane gel microparticles having a diameter of from 5 to 200 nm and organoaluminum compounds immobilized thereon.
The novel particles are, after their preparation, at least finely suspendable or soluble in all inert organic solvents. The size of the particles is from 10 nm for individual particles up to 500 microns for agglomerates.
The particles are preferably composed of [organosiloxane gel microparticle content]a[aluminoxane content]b[monomeric and oligomeric organoaluminum compound]c, where
a is from 1 to 99.9% by weight
b is from 1 to 99% by weight and
c is from 0 to 10% by weight, with the proviso that the individual components add up to 100% by weight.
a is preferably at most 50% by weight, in particular at most 20% by weight. b is preferably at least 10% by weight, in particular at least 50% by weight. b is preferably at most 90% by weight. c is preferably at least 0.1% by weight, in particular at least 0.5% by weight, and particularly preferably at least 2% by weight. c is preferably at most 5% by weight.
The organopolysiloxane content of the particles preferably consists of
from 0.5 to 80% by weight of units of the general formula
[R1dR23-dSiO1/2]xe2x80x83xe2x80x83(1),
from 0 to 99.0% by weight of units of the general formula
[R1eR22-eSiO2/2]xe2x80x83xe2x80x83(2),
from 0 to 99.5% by weight of units of the general formula
[R1fR21-fSiO3/2]xe2x80x83xe2x80x83(3) and
from 0 to 99.5% by weight of units of the general formula
[SiO4/2]xe2x80x83xe2x80x83(4),
xe2x80x83where
R1 are identical or different monovalent, Sixe2x80x94Oxe2x80x94C-bonded C1- to C30-hydrocarbon radicals optionally carrying functional groups, or hydrogen,
R2 are identical or different monovalent, SiC-bonded C1- to C30-hydrocarbon radicals optionally carrying functional groups and optionally also interrupted by the heteroatoms O, N or S, or hydrogen,
d has the value 0, 1, 2 or 3
e has the value 0, 1 or 2, and
f has the value 0 or 1.
Examples of unsubstituted radicals R1 are alkyl radicals, such as the methyl, ethyl and propyl radicals; cycloalkyl radicals, such as cyclohexane radical; and aryl radicals, such as the phenyl radical.
Examples of radicals R1 carrying functional groups are halogenated hydrocarbon radicals, preferably haloalkyl radicals, such as the 3,3,3-chloromethyl, 3-chloropropyl, 3-bromopropyl, 3,3,3-trifluoropropyl and 5,5,5,4,4,3,3-heptafluoropentyl radicals.
The radical R1 is in particular an unsubstituted C1- to C6-alkyl radical, a phenyl radical or hydrogen, in particular the methyl radical.
Examples and preferred examples of unsubstituted radicals R2 are the radicals indicated above for R1.
Examples of hydrocarbon radicals R2 carrying functional groups are halogenated hydrocarbon radicals, namely haloalkyl radicals, such as the 3,3,3-chloromethyl, 3-chloropropyl, 3-bromopropyl, 3,3,3-trifluoropropyl and 5,5,5,4,4,3,3-heptafluoropentyl radicals, and haloaryl radicals, such as the o-, m- and p-chlorophenyl radicals; hydrocarbon radicals carrying primary, secondary and tertiary amines, for example aminoalkyl radicals, such as the 2-aminoethyl, 3-aminopropyl, N-(2-aminoethyl)-3-aminopropyl, N-(2-aminoethyl)-3-amino-(2-methyl)propyl and pyrimidinyl radicals, aminoaryl radicals, such as the aminophenyl radical; quaternary ammonium radicals; hydrocarbon radicals carrying mercapto groups, such as the 2-mercaptoethyl and 3-mercaptopropyl radicals; cyanoalkyl radicals, such as the 2-cyanoethyl and 3-cyanopropyl radicals; hydrocarbon radicals carrying acrylyl groups, for example acryloxyalkyl radicals, such as 3-acryloxypropyl and 3-methacryloxypropyl radicals; hydrocarbon radicals carrying hydroxyl groups, for example hydroxyalkyl radicals, such as the hydroxypropyl radical; hydrocarbon radicals carrying phosphonic acid, phosphonato and sulfonato groups; saturated and unsaturated, linear and cyclic hydrocarbon radicals interrupted by the heteroatoms O, N or S, such as the furanyl, pyridyl and thiophenyl radicals.
Radical R2 is preferably an unsubstituted C1- to C6-alkyl radical or the phenyl radical, in particular the methyl, ethyl or propyl radical.
Further main-group elements, such as boron and aluminum, can be attached to R1 via an Sixe2x80x94Oxe2x80x94C bond or to a further oxygen atom of the hydrocarbon radicals R1 and R2 carrying functional groups.
The aluminoxane content of the particles preferably consists of
from 0.5 to 99% by weight of units of the general formula
[XiR4gR32-gAlO1/2]xe2x80x83xe2x80x83(5),
from 0 to 99% by weight of units of the general formula
[XjR4hR31-hAlO2/2]xe2x80x83xe2x80x83(6) and
from 0 to 99% by weight of units of the general formula
[AlO3/2]xe2x80x83xe2x80x83(7),
xe2x80x83where
R3 is a hydrogen atom or identical or different monovalent, Alxe2x80x94C-bonded, SiC-bonded C1- to C30-hydrocarbon radicals optionally carrying functional groups,
R4 is a hydrogen atom or identical or different monovalent, Alxe2x80x94Oxe2x80x94C-bonded C1- to C30-hydrocarbon radicals optionally carrying functional groups,
X is a halogen atom,
g has the value 0, 1 or 2,
h has the value 0 or 1,
i has the value 0, 1, 2 or 3, and
j has the value 0, 1 or 2.
h and g are preferably 0.
X is preferably a chlorine or fluorine atom.
Examples and preferred examples of radicals R3 are the alkyl, cycloalkyl and aryl radicals listed above for R1 and halogenated hydrocarbon radicals.
In particular, R3 is an unsubstituted C1- to C10-alkyl radical, phenyl radical or hydrogen, in particular the methyl, ethyl, propyl, isopropyl, butyl, isobutyl, hexyl or decyl radical.
Examples of unsubstituted radicals R4 are the alkyl, cycloalkyl and aryl radicals listed above for R1.
Examples of radicals R4 carrying functional groups are halogenated hydrocarbon radicals, such as the halogenated hydrocarbon radicals listed above for R1, and 1,3-diketone adducts.
The radical R4 is preferably an unsubstituted C1- to C6-alkyl radical or the phenyl radical, in particular the methyl, ethyl or isobutyl radical.
The monomeric, organoaluminum compound content of the particles preferably consists of compounds of the general formulae
R33-i-jR4i-jAlXjxe2x80x83xe2x80x83(8)
xe2x80x83R52AlER5ER5xe2x80x83xe2x80x83(9),
(CH2)sAl-ER5xe2x80x83xe2x80x83(10),

where
R5 is a C1- to C30-hydrocarbon radical,
Y is a group having a free pair of electrons, selected from oxygen, sulfur and NR6,
R6 is a hydrogen atom or a radical R5,
s is an integer from 3 to 30, and
R3, R4, X, i and j are as defined above.
The oligomeric, cyclic organoaluminum compound content of the particles preferably consists of compounds of the general formula
(R3AlO2/2)k(R4AlO2/2)l(XAlO2/2)mxe2x80x83xe2x80x83(13),
where
k, l and m are each an integer from 3 to 30, with the proviso that the sum k+l+m is at least three, and
R3, R4, X, i and j are as defined above.
The oligomeric, linear organoaluminum compound content of the particles preferably consists of compounds of the general formula
R32-q-rR4q-rXrAlOxe2x80x94(R3AlO2/2)n(R4AlO2/2)o(XAlO2/2)pAlR32-q-rR4q-rXrxe2x80x83xe2x80x83(14),
where
n, o and p are each integers from 0 to 50,
q and r each have a value of 0, 1 or 2, and
R3, R4 and X are as defined above.
The radical R5 is preferably a C1- to C10-alkyl radical or the phenyl radical, in particular the methyl, ethyl, propyl, isopropyl or butyl radical.
The monomeric aluminum compounds are preferably triorganoaluminum compounds containing C1- to C10-alkyl radicals, such as trimethylaluminum, triethylaluminum, triisobutylaluminum and tridecylaluminum; diorganoaluminum hydride compounds containing C1- to C10-alkyl radicals, such as dimethylaluminum hydride and didecylaluminum hydride; organoaluminum dihydride compounds, such as methylaluminum hydride; diorganoaluminum halides, such as dimethylaluminum chloride; organoaluminum dihalides, such as methylaluminum dichloride; and organoaluminum sesquihalides, such as trimethyldialuminum dichloride.
Particular preference is given here to triorganylaluminum compounds containing C1- to C10-alkyl radicals, in particular trimethylaluminum, triethylaluminum, tripropylaluminum, triisopropyl-aluminum, tri-n-butylaluminum and tridecylaluminum.
The particles preferably contain at least 5% by weight of aluminoxane and the remaining units of the particles consist of
from 1 to 80% by weight of units of the general formula (1),
from 0 to 98% by weight of units of the general formula (2),
from 0 to 99% by weight of units of the general formula (3) and
from 0 to 99% by weight of units of the general formula (4),
with the proviso that the sum of the units of the general formulae (3) and (4) is at least 1% by weight.
The particles can also contain monomeric aluminum starting compounds in an amount of from 0.01 to 50% by weight, in particular up to 10% by weight, relative to the total weight of the particles.
The invention furthermore relates to a process for the preparation of particles comprising organopolysiloxane gel microparticles having a diameter of from 5 to 200 nm and organoaluminum compounds immobilized thereon, in which organoaluminum compounds selected from compounds of the above general formulae (8) to (13) are reacted with compounds carrying hydroxyl groups in the presence of organopolysiloxane gel microparticles having a diameter of from 5 to 200 nm.
Suitable organopolysiloxane gel microparticles are preferably composed of units of the above general formulae (1) to (4). For example, the organopolysiloxane gel microparticles are methyl-, ethyl-, phenyl- or vinylpolysiloxane gel microparticles.
Particularly suitable organopolysiloxane particles for the preparation of the novel particles are those described in EP-A-744 432. Particular preference is given to the organopolysiloxane particles which are soluble to the extent of at least 5% by weight in hydrocarbons, such as aromatic, unsubstituted hydrocarbons, such as toluene, benzene and xylene, unsubstituted, aliphatic hydrocarbons, such as pentane, isopentane, isobutane, hexane and cyclohexane, in particular toluene, at 20xc2x0 C.
The organopolysiloxane particles employed may be free from reactive groups, such as hydroxyl and alkoxy groups, and only contain hydrocarbon radicals.
Other very suitable organopolysiloxane particles are those described in EP-A-744 432 which contain a total of more than 15% by weight of units of the above general formulae (1) to (4) which carry one or three Sixe2x80x94C-bonded radicals R2 and have not been freed from residual OH or hydrocarbonoxy groups in a third step.
The organoaluminum compounds of the general formulae (8) to (13) which can be used react with compounds containing hydroxide [sic] groups to form aluminoxanes.
The organoaluminum compounds can be employed in the form of solids, liquids or gases. They are preferably used in the form of liquids or in solution.
Preference is given to the monomeric organoaluminum compounds described above as preferred under the general formulae (8) to (13).
If the organoaluminum compounds are employed in solution, preferred solvents are the hydrocarbons which are listed above as preferred solvents for the organopolysiloxane gel microparticles.
The organopolysiloxane gel microparticles are preferably also employed dissolved in the above-described hydrocarbons.
The dissolved reaction partners are preferably then mixed. If desired, the organoaluminum compounds can also be dissolved directly in the organopolysiloxane gel microparticle solution.
The preferred concentrations of organopolysiloxane gel microparticles and of the organoaluminum compounds are at least 1% by weight, at most 50% by weight, in particular at most 30% by weight, particularly preferably at most 20% by weight, based on the total weight of the solution.
The compounds carrying hydroxide [sic] groups are preferably water, C1- to C40-hydrocarbons carrying hydroxide [sic] groups, such as primary, secondary and tertiary alcohols, diols, triols, phenols and sugars, or inorganic compounds carrying hydroxide [sic] groups, such as boric acid or aluminum hydroxide. Particular preference is given to water, which can be added as such in solid, liquid or gas form, as water of crystallization, or as an emulsion or microemulsion.
The molar ratios between hydroxyl groups and the organoaluminum compound is preferably varied in a molar ratio of from 0.01:1 to 10:1.
The compounds carrying hydroxyl groups are preferably added with stirring. The temperatures during this addition are preferably from xe2x88x9280xc2x0 C. to 250xc2x0 C., in particular from xe2x88x9220xc2x0 C. to 100xc2x0 C., and particularly preferably from xe2x88x9240xc2x0 C. to 0xc2x0 C.
The reactions are then preferably continued at a temperature in the range from xe2x88x9280xc2x0 C. to 200xc2x0 C., in particular at a temperature in the range from xe2x88x9280xc2x0 C. to 140xc2x0 C., particularly preferably at a temperature in the range from 0xc2x0 C. to 80xc2x0 C.
The reaction can be carried out with mixing, but can also be carried out without mixing. Mixing of the reaction solution is preferred.
The reaction times are between a few minutes and one day, preferably between one hour and ten hours, particularly preferably between 5 minutes and two hours. The end point of the reaction can be determined from the end of gas evolution.
When a solvent is used during the reaction, the finished particles form a suspension, which can be employed for further reactions or uses, for example as cocatalyst.
The finished particles can also preferably be filtered off under an inert-gas atmosphere, preferably argon, and at the abovementioned temperatures, and rinsed with a solvent, such as a hydrocarbon.
The filter cake can preferably then be dried in a high vacuum, for example at room temperature. The cocatalyst can also, if desired, be stored under an inert gas in the moist state without further drying.
Another variant of the work-up is removal of the solvent under reduced pressure.
The invention furthermore relates to the use of the particles as cocatalysts together with metal compounds from sub-group 4, 5, 6 and 8-10 of the Periodic Table, for the oligomerization, cyclization or polymerization of olefins.
The metal catalysts from sub-group 4, 5, 6 and 8-10 of the Periodic Table and the particles as cocatalysts are used to prepare an immobilized and activated catalyst system, preferably in an inert solvent, in particular in a hydrocarbon, namely an aromatic, unsubstituted hydrocarbon, such as toluene, benzene or xylene, or an unsubstituted, aliphatic hydrocarbon, such as pentane, isopentane, isobutane, hexane or cyclohexane, in particular toluene.
To this end, the particles are, for example, employed directly in the suspension obtained from the preparation or are suspended, dispersed or partially dissolved in a suitable inert solvent, preferably under an inert gas, such as argon. Suitable inert solvents are the abovementioned hydrocarbons. Particles are then mixed with metal catalyst, preferably with stirring. The metal catalyst can be in the solid state or suspended, dispersed, partially dissolved or dissolved in a suitable inert solvent, in this case the above hydrocarbons are preferred.
The mixing of the particles with the metal catalyst can be carried out at from xe2x88x9280xc2x0 C. to 200xc2x0 C. Preference is given to a temperature range of from xe2x88x9240xc2x0 C. to 60xc2x0 C., in particular at temperatures of 0xc2x0 C. to 30xc2x0 C. The temperature during the subsequent reaction is preferably in the above-described temperatures ranges.
Mixing can take place during the reaction, but the reaction can also be carried out without mixing. Preference is given to mixing of the reaction solution. The reaction times are preferably from 1 minute to one day, preferably from 1 minute to 10 hours, particularly preferably from 1 minute to 2 hours.
The immobilized and activated catalyst system is preferably filtered off at the abovementioned temperatures, preferably under an inert-gas atmosphere, in particular argon, and is preferably rinsed with an inert solvent, such as the abovementioned hydrocarbons. The colored filter cake can then be dried in a high vacuum, preferably at from xe2x88x9250xc2x0 C. to 100xc2x0 C. The immobilized and activated catalyst system can, if desired, also be stored under an inert gas in the moisture state without further drying.
The ratio between metal in the metal catalyst and aluminum in the particles can be set to any desired value. This ratio can be determined by elemental analysis.
The metal compounds used are preferably metallocenes and semisandwich compounds of the sub-group metals of the Periodic Table. Such metal compounds are described, for example, in U.S. Pat. No. 4,925,821. Preference is given to metal compounds containing cyclopentadienyl ligands. Preferred metals in the metal compounds are titanium, zirconium, vanadium and niobium.
The invention furthermore relates to the use of the particles as cocatalysts, together with metal compounds from sub-groups 4, 5, 6 and 8-10 of the Periodic Table, for the oligomerization, cyclization or polymerization of olefins.
The metal catalysts from sub-group 4, 5, 6 and 8-10 of the Periodic Table and the particles as cocatalysts are used to prepare an immobilized and activated catalyst system, preferably in an inert solvent, in particular in a hydrocarbon, namely an aromatic, unsubstituted hydrocarbon, such as toluene, benzene or xylene, or an unsubstituted, aliphatic hydrocarbon, such as pentane, isopentane, isobutane, hexane or cyclohexane, in particular toluene.
The particles and the immobilized and activated catalyst systems prepared therewith together with metal compounds can be dried immediately after their preparation, used without drying or employed only after storage for any desired time, without any drop in activity, for the oligomerization, cyclization or polymerization of olefins, in batch processes or continuous processes.
For the polymerization of olefins, these catalyst systems are introduced into the reactor at the outset or added continuously, as a suspension with solvent or without solvent for a gas-phase reaction or fluidized-bed process. Solvents which are suitable for the polymerization of olefins are the inert hydrocarbons described above. The olefin to be polymerized, such as propene, can itself also serve as solvent.
In the next step of olefin polymerization, the monomer or monomer mixture, if it is not already present as solvent, is added in one portion or continuously or, in the case of copolymerizations, successively, in solid, liquid or gas form.
Examples of suitable olefins are, depending on the catalyst system used, linear or cyclic C2- to C30-mono-1-olefins, such as ethylene, propylene, 1-hexene, cyclopentene, cyclohexene and norbornene, likewise polyunsaturated, linear or cyclic C4- to C30-olefins, such as 1,3-butadiene, isoprene, 1,3-pentadiene, styrene, xcex1-methylstyrene and norbornadiene. All the above olefins can be homopolymerized and copolymerized in any desired ratios.
The reaction can be carried out with mixing. The reaction temperature is preferably from xe2x88x9280xc2x0 C. to 200xc2x0 C., in particular from 0xc2x0 C. to 140xc2x0 C., particularly preferably from 60xc2x0 C. to 120xc2x0 C. The pressure during the reaction can preferably be varied from 1 bar to 400 bar.
The product obtained can be processed further without further work-up. If desired, the polymer can also be subsequently treated with alkaline, aqueous media, such as sodium hydroxide solution, but this is not preferred.
In the examples below, unless otherwise specified,
a) all amounts are by weight
b) all pressures are 0.10 MPa (abs.)
c) all temperatures are 20xc2x0 C.